com.hazelcast.internal.util.ThreadAffinity Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2024, Hazelcast, Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hazelcast.internal.util;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
import static com.hazelcast.internal.util.ThreadAffinityHelper.isAffinityAvailable;
/**
* Contains the thread affinity logic for certain threads.
*
* Inside is a list of CPU bitmaps and using the {@link #nextAllowedCpus()} there is a round-robin
* over the list of the CPU bitmaps. The reason for a round-robin is that the same ThreadAffinity can
* be used when threads get stopped and new threads created.
*
* This class is threadsafe.
*/
@SuppressWarnings("java:S112")
public class ThreadAffinity {
public static final ThreadAffinity DISABLED = new ThreadAffinity(null);
final List allowedCpusList;
final AtomicInteger threadIndex = new AtomicInteger();
public ThreadAffinity(String affinity) {
allowedCpusList = parse(affinity);
if (allowedCpusList.isEmpty()) {
return;
}
if (!isAffinityAvailable()) {
throw new RuntimeException("Can't use affinity '" + affinity + "'. Thread affinity support is not available.");
}
}
/**
* Creates a new ThreadAffinity based on a system property.
*
* If no property is set, then affinity is disabled.
*
* @param property the name of the system property.
* @return the created ThreadAffinity.
* @throws InvalidAffinitySyntaxException if there is a problem with the value.
*/
public static ThreadAffinity newSystemThreadAffinity(String property) {
String value = System.getProperty(property);
try {
return new ThreadAffinity(value);
} catch (InvalidAffinitySyntaxException e) {
throw new InvalidAffinitySyntaxException("Invalid affinity syntax for System property '" + property + "'."
+ " Value '" + value + "'. "
+ " Errormessage '" + e.getMessage() + "'");
}
}
static List parse(String affinity) {
List cpus = new ArrayList<>();
if (affinity == null) {
return cpus;
}
affinity = affinity.trim();
if (affinity.isEmpty()) {
return cpus;
}
List groups = new AffinityParser(affinity).parse();
for (CpuGroup group : groups) {
BitSet allowedCpus = new BitSet();
for (Integer cpu : group.cpus) {
allowedCpus.set(cpu);
}
for (int k = 0; k < group.threadCount; k++) {
cpus.add(allowedCpus);
}
}
return cpus;
}
public int getThreadCount() {
return allowedCpusList.size();
}
public BitSet nextAllowedCpus() {
if (allowedCpusList.isEmpty()) {
return null;
}
int index = threadIndex.getAndIncrement() % allowedCpusList.size();
return allowedCpusList.get(index);
}
public boolean isEnabled() {
return !allowedCpusList.isEmpty();
}
static class AffinityParser {
private final String string;
private final List groups = new ArrayList<>();
private int index;
private int digit;
private int integer;
private int fromRange;
private int toRange;
AffinityParser(String string) {
this.string = string;
}
List parse() {
if (!expression() || index < string.length()) {
throw new InvalidAffinitySyntaxException("Syntax Error at " + index);
}
// verification that we have no duplicate cpus.
BitSet usedCpus = new BitSet();
for (CpuGroup group : groups) {
for (Integer cpu : group.cpus) {
if (usedCpus.get(cpu)) {
throw new InvalidAffinitySyntaxException("Duplicate CPU found, offending CPU=" + cpu);
}
usedCpus.set(cpu);
}
}
return groups;
}
boolean expression() {
if (!item()) {
return false;
}
while (character(',')) {
if (!item()) {
return false;
}
}
return true;
}
boolean item() {
if (range()) {
for (int cpu = fromRange; cpu <= toRange; cpu++) {
CpuGroup group = new CpuGroup();
group.cpus.add(cpu);
group.threadCount = 1;
groups.add(group);
}
return true;
} else {
return group();
}
}
boolean range() {
if (!integer()) {
return false;
}
fromRange = integer;
toRange = integer;
if (character('-')) {
if (!integer()) {
return false;
}
toRange = integer;
if (toRange < fromRange) {
error("ToRange can't smaller than fromRange, toRange=" + toRange + " fromRange=" + fromRange + ".");
}
}
return true;
}
private void error(String error) {
throw new InvalidAffinitySyntaxException(error + " at index:" + index);
}
@SuppressWarnings("checkstyle:NPathComplexity")
boolean group() {
if (!character('[')) {
return false;
}
if (!range()) {
return false;
}
CpuGroup group = new CpuGroup();
addCpuRangeToGroup(group);
while (character(',')) {
if (!range()) {
return false;
}
addCpuRangeToGroup(group);
}
if (!character(']')) {
return false;
}
if (character(':')) {
if (!integer()) {
return false;
}
group.threadCount = integer;
if (group.threadCount == 0) {
error("Thread count can't be 0.");
} else if (group.threadCount > group.cpus.size()) {
error("Thread count can't be larger than number of cpu's in the group. "
+ "Thread count = " + group.threadCount + " cpus:" + group.cpus);
}
} else {
group.threadCount = group.cpus.size();
}
groups.add(group);
return true;
}
private void addCpuRangeToGroup(CpuGroup group) {
for (int k = fromRange; k <= toRange; k++) {
group.cpus.add(k);
}
}
@SuppressWarnings("checkstyle:magicnumber")
boolean integer() {
if (!digit()) {
return false;
}
integer = digit;
for (; ; ) {
if (!digit()) {
return true;
}
integer = integer * 10;
integer += digit;
}
}
boolean digit() {
if (index >= string.length()) {
return false;
}
char c = string.charAt(index);
if (Character.isDigit(c)) {
index++;
digit = Character.getNumericValue(c);
return true;
} else {
return false;
}
}
boolean character(char expected) {
if (index >= string.length()) {
return false;
}
char c = string.charAt(index);
if (c == expected) {
index++;
return true;
} else {
return false;
}
}
}
static class InvalidAffinitySyntaxException extends RuntimeException {
InvalidAffinitySyntaxException(String message) {
super(message);
}
}
static class CpuGroup {
List cpus = new LinkedList<>();
int threadCount = -1;
@Override
public String toString() {
return "CpuGroup{"
+ "cpus=" + cpus
+ ", count=" + threadCount
+ '}';
}
}
}